Senate Majority Leader Bill Frist Friday expressed his support for legislation to expand federal funding of embryonic stem cell research. The position puts him at odds with President Bush and religious conservatives, whose support he may need if he makes a run for the White House in 2008.

In a speech on the Senate floor, Senator Frist signaled his support for House-passed legislation that would allow research on frozen human embryos left over from fertility treatments. The measure would lift restrictions imposed by President Bush in 2001.

The Tennessee Republican, who is also a heart and lung surgeon, said loosening the limitations imposed by the President could bring potential new treatments for certain diseases. "Stem cells offer hope for treatment that other lines of research simply cannot offer," he said.

Supporters of the bill say such research could offer treatment of incurable conditions, including some forms of cancer and Alzheimer's disease.

The announcement was welcomed by Senator Arlen Specter, a Pennsylvania Republican, who is sponsoring stem cell legislation and who is also a cancer patient. "I believe that the speech he has just made on the Senate floor is the most important speech made this year," said Senator Specter.

The top Democrat in the Senate, Senator Harry Reid of Nevada, echoed the comments. "It was a moral decision made by the Majority Leader of the United States Senate," he said, "a decision that will bring hope to millions of Americans."

Opponents of expanding stem cell research, who believe life begins at conception, say the procedure is wrong because it involves the destruction of an embryo. Among those opponents is President Bush, who is standing by his decision to veto the legislation. "Taxpayer money should not be used to create life for the sole purpose of destroying it," said White House spokesman Scott McClellan.

Senator Frist is seen as a likely candidate for president in 2008, and his announcement could have an impact on his support among religious conservatives, who helped elect President Bush in 2000 and again in 2004. In making his announcement, Mr. Frist said his position is anchored in his religious faith, saying he remains pro-life. But he said the issue to him is not just a matter of faith, it is a matter of science.

Immediately after the speech, the Christian Defense Coalition issued a statement saying Senator Frist should not expect support and endorsement from the pro-life community if he votes for embryonic research funding. Although Mr. Frist's announcement could alienate many anti-abortion conservatives, it could also attract support from moderate voters.

The Senate, where the legislation had stalled before the Senate Majority Leader's comments, could take up the measure after it returns from its August recess.